The problem with that of course is reinstalling all the programs that you do actually need it’s not all junk on your pc. I did exactly what you did frequently and then discovered that Norton for example only allows a limited number of installations and I had to go out and pay for a new cd.
I found that software vendors are in three categories, with regard to re-installation on the same hardware:
In my experience, license managers (e.g. FlexLM), Adobe, and Norton/Symantec are among the worst offenders. But there are always alternatives, and I believe in applying market pressure by voting with my wallet. If they sell me a crippled product, it'll be the last one I buy from them.